Wiper drive mechanism with a reversible gear motor

ABSTRACT

A wiper drive ( 10, 12, 14 ) with a reversible geared motor ( 16 ) is fastened to a motor mounting plate ( 18 ). The driven shaft ( 22 ) of the wiper drive supports a crank ( 28, 30, 32 ), which is connected by means of at least one joint ( 34, 36, 38, 40 ) to a leaver ( 68, 70 ) of a lever mechanism. The crank is a crank plate ( 28, 30, 32 ) on which at least two adjacent joints ( 34, 36 ) for two levers ( 68, 70 ) are disposed adjacent to each other in a plane.

BACKGROUND OF THE INVENTION

The invention is based on a wiper drive with a reversible geared motor.

Wiper systems of motor vehicles are as a rule fastened with a wipersupport, a so-called mounting plate, to the body of a motor vehicle. Themounting plate supports a wiper drive with a wiper motor and atransmission built into it, whose driven shaft, as a rule by means of adriving crank and joint rods, drives cranks which are connected to adrive shaft for each wiper. The joint rods are linked to the drivingcrank by means of two ball-and-socket joints, wherein the joint axesextend coaxially. A lever mechanism of this kind comprised of the cranksand joint rods takes up a correspondingly large amount of structuralspace in the vehicle due to its structural height.

EP 0 781 691 A1 has disclosed a wiper drive which is comprised of anelectric motor with a worm gear and a lever mechanism. An offset drivingcrank is supported on the driven shaft. A joint rod, which is connectedto the driving crank by means of a ball-and-socket joint, is connectedat its free end, likewise by means of a ball-and-socket joint, to acrank embodied as a crank plate, which is connected to a drive shaft ofa wiper. By means of another ball-and-socket joint, the crank plate isengaged by a second joint rod, which is connected with its free end to acrank, which is fastened to a drive shaft for a second wiper. The levermechanism comprised of the cranks and joint rods is very expensive andtakes up a relatively large amount of structural space. Furthermore, thejoint rod that leads from the driving crank to the crank of the firstwiper is subjected to the driving forces of both wipers. The first jointrod and its joints must be designed accordingly.

EP 0 683 739 has disclosed a joint in which three joint parts areprovided with concentrically arranged ball-shaped bearing surfaces. Eachjoint part is connected to a joint rod or to a driving crank. Theconnections of the driving crank and the joint rods require a largeamount of axial space in the direction of the common pivot axis.

SUMMARY OF THE INVENTION

According to the invention, the wiper drive is comprised of a reversiblegeared motor whose driven shaft is connected to a driving crank which isembodied as a crank plate and drives two joint rods by means of twojoints that are suitably embodied as ball-and-socket joints. These twojoint rods are connected to cranks which are each connected to a driveshaft of the two respective wipers. The cranks and joint rods constitutea lever mechanism. The reversible geared motor, which replaces aconventional rotating motor, pivots the installed crank only in alimited angular range, e.g. up to 180° around the axis of the drivenshaft. As a result, the joints can, according to the invention, bedisposed next to each other in one plane on the crank plate, so that avery flat lever mechanism is produced.

According to one embodiment of the invention, the joints on the drivingcrank plate are disposed at different distances from the driven shaft.As a result, differences in the lever transmission that result from anasymmetrical position of the driven shaft in relation to the driveshafts of the wipers can be balanced out. Furthermore, differentkinematics can be produced for a wiper on the driver's side and a wiperon the passenger side.

As a rule, the geared motor is screwed to a motor mounting plate bymeans of a screw, while the driving crank is fastened to the drivenshaft with a screw. In order to limit the structural height in thedirection of the driven shaft, it is suitable to offset the crankplate—in fact in such a way that its free end is a greater distance fromthe motor mounting plate than the part supported on the drive shaft. Asa result, a space is created for the fastening screws of the gearedmotor, without increasing the structural height in the direction of thedrive axis. There is also the possibility of fastening ball journalsonto the crank plate, which point toward the motor mounting plate andconsequently also do not increase the structural space in the directionof the drive axis. This type of articulation is also advantageous ifonly one joint rod engages the crank plate.

Since the joint rods are each subjected to only the driving forces forone wiper, they can be embodied as thin-walled and lightweight. Oneembodiment of the invention suggests incorporating the support socket ofthe ball-and-socket joint into the crank plate. Since the crank platemust be embodied as correspondingly thick in order, if necessary, totransmit double the driving forces, namely for two wipers, the jointballs and the support sockets can be embodied as sufficiently largewithout increasing the structural space as a result. In this connection,the joint ball can be provided with a pin on one side or can be providedwith two diametrically opposed pins. In the second case, the joint rodhas a fork-shaped end which is connected to the two pins, e.g. byrivets. The articulating lever can be embodied as very lightweight bybeing comprised of two bent sheet metal parts which are connected toeach other at a central joint extending parallel to the fork-shapedends.

Other advantages ensue from the following description of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are shown in the drawings. Thedrawings, the description, and the claims contain numerous features incombination. The specialist will also suitably consider the featuresindividually and will combine them into other logical combinations.

FIG. 1 is a perspective depiction of a crank plate with two joints,

FIG. 2 is a partial longitudinal section through a variant with anoffset crank plate, and

FIG. 3 shows a variant with a joint that is incorporated into the crankplate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The wiper drives 10, 12, 14 according to FIGS. 1 to 3 have a reversiblegeared motor 16 shown in FIG. 2, which is connected by means of screws20 to a motor mounting plate 18. A crank plate 28, 30, 32 is screwed toits driven shaft 22 with a screw 26. The geared motor 16 pivots thecrank plate 28, 30, 32 in a limited angular range, preferably up to180°, around an axis 24 of the driven shaft 22.

In the embodiment according to FIG. 1, the crank plate 28 is flat andsupports two adjacent ball pins 44, 46 of joints 34, 36, which are eachdisposed a respective distance 62, 64 from the axis 24 of the drivenshaft 22. The distances 62, 64 can be equal. However, they can also bedesigned to be different in order to embody the kinematics for the twowipers differently or in order to compensate for an asymmetricalposition of the driven shaft 22 in relation to the drive shafts of thewipers. The height of the structural space required is essentiallydetermined only by the thickness of the crank plate 28 and the height ofthe ball pins 44, 46.

The embodiment according to FIG. 2 differs from the embodiment accordingto FIG. 1 essentially in that the crank plate 30 is offset so that itsfree end is a greater distance 66 from the motor mounting plate 18 thanthe part supported by the driven shaft 22. This creates space for thefastening screws 20 of the geared motor 16. Furthermore, the greaterdistance 66 can be used for ball pins 48 whose pins 52 are riveted tothe crank plate 30. The ball-shaped part of the ball pin 48 protrudingtoward the motor mounting plate 18 is encompassed by a support socket 58which is suitably made of plastic and is injection molded onto a jointrod 68. The space available in the direction of the axis 24 of thedriven shaft 22 is optimally utilized due to the parallel disposition ofthe drive shaft 22, the screw 20 for fastening the geared motor, and thejoint 38.

In the embodiment according to FIG. 3, the crank plate. 32 is flat.However, it can also be offset similarly to the one shown in FIG. 2. Itdiffers from the embodiments described above in that a support socket 60made of plastic is injection molded into the crank plate 32 andencompasses a ball pin 50 in the vicinity of its ball-shaped contour.The ball pin 50 has two pins 54, 56, which are disposed diametricallyopposite one another and are riveted to a fork-shaped end 72 of thejoint rod 70. The joint rod 70 is comprised of two bent sheet metalparts which are connected to each other at a joint 42. The joint 42extends in a central longitudinal plane of the joint rod 70, parallel tothe fork-shaped end 72. The wall thickness of the crank plate 32 hasenough space to contain the joint 40, while the thin-walled joint rod 70does not increase the structural space in the direction of the axis 24of the driven shaft 22. The embodiment according to FIG. 3 can also havetwo or more joints, similar to the embodiment according to FIG. 1.

What is claimed is:
 1. A wiper drive (10, 12, 14), comprising: areversible geared motor (16), said geared motor (16) fastened to a motormounting plate (18), said wiper drive having a driven shaft (22), saiddriven shaft (22) supporting a crank (28, 30, 32), said crank (28, 30,32) connected by means of at least one joint (34, 36, 38, 40) to a lever(68, 70) of a lever mechanism, wherein the crank is a crank plate (28,30, 32) on which at least two joints (34, 36) for two levers (68, 70)are disposed adjacent to each other in a plane, wherein at least onesupport socket (60) is incorporated into the crank plate (32) andsupports a ball pin (50) with its ball, wherein the ball pin (50) hastwo diametrically opposed pins (54, 56), and wherein said opposed pins(54, 56) are fastened to a fork-shaped end (72) of one of said twolevers (70).
 2. The wiper drive (12) according to claim 1, wherein thecrank plate (30) is offset and its free end is a greater distance (66)from the motor mounting plate (18) than the part supported by the drivenshaft (22).
 3. The wiper drive (12) according to the preamble of claim1, characterized in that at least one ball pin (48) is fastened to thecrank plate (30), pointing toward the motor mounting plate (18).
 4. Thewiper drive (14) according to claim 1, wherein the lever (70) iscomprised of two bent sheet metal parts and has a joint (42) whichextends in a longitudinal central plane parallel to the fork-shaped end(72).
 5. A wiper drive (10, 12, 14), comprising: reversible geared motor(16), said geared motor (16) fastened to a motor mounting plate (18),said wiper drive having a driven shaft (22), said driven shaft (22)supporting a crank (28, 30, 32), said crank (28, 30, 32) connected bymeans of at least one joint (34, 36, 38, 40) to a lever (68, 70) of alever mechanism, wherein the crank is a crank plate (28, 30, 32) onwhich at least two joints (34, 36) for two levers (68, 70) are disposedadjacent to each other in a plane, wherein the crank plate (30) isoffset in form, whereby a free end of said crank plate (30) is a greaterdistance (66) from the motor mounting plate (18) than a part supportedby the driven shaft (22), wherein at least one ball pin (48) is fastenedto the crank plate (30), pointing toward the motor mounting plate (18).